ewah_read_mmap: bounds-check mmap reads
[git/git.git] / ewah / ewok.h
1 /**
2 * Copyright 2013, GitHub, Inc
3 * Copyright 2009-2013, Daniel Lemire, Cliff Moon,
4 * David McIntosh, Robert Becho, Google Inc. and Veronika Zenz
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version 2
9 * of the License, or (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, see <http://www.gnu.org/licenses/>.
18 */
19 #ifndef __EWOK_BITMAP_H__
20 #define __EWOK_BITMAP_H__
21
22 struct strbuf;
23 typedef uint64_t eword_t;
24 #define BITS_IN_EWORD (sizeof(eword_t) * 8)
25
26 /**
27 * Do not use __builtin_popcountll. The GCC implementation
28 * is notoriously slow on all platforms.
29 *
30 * See: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36041
31 */
32 static inline uint32_t ewah_bit_popcount64(uint64_t x)
33 {
34 x = (x & 0x5555555555555555ULL) + ((x >> 1) & 0x5555555555555555ULL);
35 x = (x & 0x3333333333333333ULL) + ((x >> 2) & 0x3333333333333333ULL);
36 x = (x & 0x0F0F0F0F0F0F0F0FULL) + ((x >> 4) & 0x0F0F0F0F0F0F0F0FULL);
37 return (x * 0x0101010101010101ULL) >> 56;
38 }
39
40 /* __builtin_ctzll was not available until 3.4.0 */
41 #if defined(__GNUC__) && (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR > 3))
42 #define ewah_bit_ctz64(x) __builtin_ctzll(x)
43 #else
44 static inline int ewah_bit_ctz64(uint64_t x)
45 {
46 int n = 0;
47 if ((x & 0xffffffff) == 0) { x >>= 32; n += 32; }
48 if ((x & 0xffff) == 0) { x >>= 16; n += 16; }
49 if ((x & 0xff) == 0) { x >>= 8; n += 8; }
50 if ((x & 0xf) == 0) { x >>= 4; n += 4; }
51 if ((x & 0x3) == 0) { x >>= 2; n += 2; }
52 if ((x & 0x1) == 0) { x >>= 1; n += 1; }
53 return n + !x;
54 }
55 #endif
56
57 struct ewah_bitmap {
58 eword_t *buffer;
59 size_t buffer_size;
60 size_t alloc_size;
61 size_t bit_size;
62 eword_t *rlw;
63 };
64
65 typedef void (*ewah_callback)(size_t pos, void *);
66
67 struct ewah_bitmap *ewah_pool_new(void);
68 void ewah_pool_free(struct ewah_bitmap *self);
69
70 /**
71 * Allocate a new EWAH Compressed bitmap
72 */
73 struct ewah_bitmap *ewah_new(void);
74
75 /**
76 * Clear all the bits in the bitmap. Does not free or resize
77 * memory.
78 */
79 void ewah_clear(struct ewah_bitmap *self);
80
81 /**
82 * Free all the memory of the bitmap
83 */
84 void ewah_free(struct ewah_bitmap *self);
85
86 int ewah_serialize_to(struct ewah_bitmap *self,
87 int (*write_fun)(void *out, const void *buf, size_t len),
88 void *out);
89 int ewah_serialize(struct ewah_bitmap *self, int fd);
90 int ewah_serialize_native(struct ewah_bitmap *self, int fd);
91 int ewah_serialize_strbuf(struct ewah_bitmap *self, struct strbuf *);
92
93 int ewah_deserialize(struct ewah_bitmap *self, int fd);
94 ssize_t ewah_read_mmap(struct ewah_bitmap *self, const void *map, size_t len);
95
96 uint32_t ewah_checksum(struct ewah_bitmap *self);
97
98 /**
99 * Logical not (bitwise negation) in-place on the bitmap
100 *
101 * This operation is linear time based on the size of the bitmap.
102 */
103 void ewah_not(struct ewah_bitmap *self);
104
105 /**
106 * Call the given callback with the position of every single bit
107 * that has been set on the bitmap.
108 *
109 * This is an efficient operation that does not fully decompress
110 * the bitmap.
111 */
112 void ewah_each_bit(struct ewah_bitmap *self, ewah_callback callback, void *payload);
113
114 /**
115 * Set a given bit on the bitmap.
116 *
117 * The bit at position `pos` will be set to true. Because of the
118 * way that the bitmap is compressed, a set bit cannot be unset
119 * later on.
120 *
121 * Furthermore, since the bitmap uses streaming compression, bits
122 * can only set incrementally.
123 *
124 * E.g.
125 * ewah_set(bitmap, 1); // ok
126 * ewah_set(bitmap, 76); // ok
127 * ewah_set(bitmap, 77); // ok
128 * ewah_set(bitmap, 8712800127); // ok
129 * ewah_set(bitmap, 25); // failed, assert raised
130 */
131 void ewah_set(struct ewah_bitmap *self, size_t i);
132
133 struct ewah_iterator {
134 const eword_t *buffer;
135 size_t buffer_size;
136
137 size_t pointer;
138 eword_t compressed, literals;
139 eword_t rl, lw;
140 int b;
141 };
142
143 /**
144 * Initialize a new iterator to run through the bitmap in uncompressed form.
145 *
146 * The iterator can be stack allocated. The underlying bitmap must not be freed
147 * before the iteration is over.
148 *
149 * E.g.
150 *
151 * struct ewah_bitmap *bitmap = ewah_new();
152 * struct ewah_iterator it;
153 *
154 * ewah_iterator_init(&it, bitmap);
155 */
156 void ewah_iterator_init(struct ewah_iterator *it, struct ewah_bitmap *parent);
157
158 /**
159 * Yield every single word in the bitmap in uncompressed form. This is:
160 * yield single words (32-64 bits) where each bit represents an actual
161 * bit from the bitmap.
162 *
163 * Return: true if a word was yield, false if there are no words left
164 */
165 int ewah_iterator_next(eword_t *next, struct ewah_iterator *it);
166
167 void ewah_or(
168 struct ewah_bitmap *ewah_i,
169 struct ewah_bitmap *ewah_j,
170 struct ewah_bitmap *out);
171
172 void ewah_and_not(
173 struct ewah_bitmap *ewah_i,
174 struct ewah_bitmap *ewah_j,
175 struct ewah_bitmap *out);
176
177 void ewah_xor(
178 struct ewah_bitmap *ewah_i,
179 struct ewah_bitmap *ewah_j,
180 struct ewah_bitmap *out);
181
182 void ewah_and(
183 struct ewah_bitmap *ewah_i,
184 struct ewah_bitmap *ewah_j,
185 struct ewah_bitmap *out);
186
187 /**
188 * Direct word access
189 */
190 size_t ewah_add_empty_words(struct ewah_bitmap *self, int v, size_t number);
191 void ewah_add_dirty_words(
192 struct ewah_bitmap *self, const eword_t *buffer, size_t number, int negate);
193 size_t ewah_add(struct ewah_bitmap *self, eword_t word);
194
195
196 /**
197 * Uncompressed, old-school bitmap that can be efficiently compressed
198 * into an `ewah_bitmap`.
199 */
200 struct bitmap {
201 eword_t *words;
202 size_t word_alloc;
203 };
204
205 struct bitmap *bitmap_new(void);
206 void bitmap_set(struct bitmap *self, size_t pos);
207 void bitmap_clear(struct bitmap *self, size_t pos);
208 int bitmap_get(struct bitmap *self, size_t pos);
209 void bitmap_reset(struct bitmap *self);
210 void bitmap_free(struct bitmap *self);
211 int bitmap_equals(struct bitmap *self, struct bitmap *other);
212 int bitmap_is_subset(struct bitmap *self, struct bitmap *super);
213
214 struct ewah_bitmap * bitmap_to_ewah(struct bitmap *bitmap);
215 struct bitmap *ewah_to_bitmap(struct ewah_bitmap *ewah);
216
217 void bitmap_and_not(struct bitmap *self, struct bitmap *other);
218 void bitmap_or_ewah(struct bitmap *self, struct ewah_bitmap *other);
219 void bitmap_or(struct bitmap *self, const struct bitmap *other);
220
221 void bitmap_each_bit(struct bitmap *self, ewah_callback callback, void *data);
222 size_t bitmap_popcount(struct bitmap *self);
223
224 #endif